This application relates generally to mounting data storage devices and more particularly to mounting a disc drive to a planar surface using a mounting means located about the center-of-mass of the disc drive.
Disc drives are commonly used in workstations, personal computers, portables and other computer systems to store large amounts of data in a form that can be made readily available to a user. In general, a disc drive comprises one or more magnetic discs that are rotated by a spindle motor at a constant high speed. The surface of each disc is divided into a series of data tracks which are spaced radially from one another across a band having an inner diameter and an outer diameter. The data tracks extend circumferentially around the discs and store data in the form of magnetic flux transitions within the radial extent of the tracks on the disc surfaces. Typically, each data track is divided into a number of data sectors that store fixed size data blocks.
A head includes an interactive element such as a magnetic transducer which senses the magnetic transitions on a selected data track to read the data stored on the track, or to transmit an electrical signal that induces magnetic transitions on the selected data track to write data to the track. The head includes a read/write gap that positions the active elements of the head at a position suitable for interaction with the magnetic transitions on the data tracks of a disc as the disc rotates.
As is known in the art, each head is mounted to a rotary actuator arm and is selectively positionable by the actuator arm over a preselected data track of the disc to either read data from or write data to the preselected data track. The head includes a slider assembly having an air bearing surface that causes the head to fly over the data tracks of the disc surface due to fluid air currents caused by rotation of the disc.
Typically, several discs are stacked on top of each other and the surfaces of the stacked discs are accessed by the heads mounted on a complementary stack of actuator arms which comprise an actuator assembly, or xe2x80x9cE-block.xe2x80x9d The E-block generally includes head wires which conduct electrical signals from the heads to a flex circuit, which in turn conducts the electrical signals to a printed circuit board (PCB) mounted to a disc drive base deck.
Control of the movement of the read/write heads from track to track on the disc surfaces is commonly accomplished through the use of a closed-loop servo system. Such servo systems typically make use of servo information recorded on the disc surfaces at the time of manufacture to obtain general information defining the specific track number and the sector position of the disc relative to the read/write head. When an access command is sent to the disc drive, a comparison is internally made between the current position of the read/write heads relative to the disc and the location at which the desired data transfer is to take place. If the read/write heads are currently positioned over the desired tracks, the disc drive simply waits for the correct circumferential location to rotate under the read/write heads, and begins the requested data transfer. If, however, the data transfer is to take place at a location other than the current position of the actuator, the servo logic determines both the distance and direction in which the actuator must move in order to bring the read/write heads to the target track. Based on this determination, the servo logic applies controlled direct current to the coil of the actuator voice coil motor (VCM), which causes the actuator to move from the current track location to the target track.
During such xe2x80x9ctrack seekingxe2x80x9d operations, the servo logic monitors the dynamic position of the actuator by reading the prerecorded servo data from the disc surfaces during the seek, and controls the current applied to the VCM in a manner to bring the read/write heads to rest at the target track.
A second function of the servo system is to maintain the read/write heads over the centerline of the target track, so that data transfers can be accomplished without inadvertently accessing adjacent tracks. This xe2x80x9ctrack followingxe2x80x9d function is accomplished by constantly monitoring a position error signal (PES) which is proportional to the relationship of the read/write heads to the track centerline. That is, when the read/write heads are perfectly centered on the data track, the PES is zero, and no current is applied to the actuator VCM. Any tendency of the read/write heads to move away from the track centerline results in the generation of a PES with a polarity reflective of the direction in which the read/write head is displaced from the track centerline. The PES is then used by the servo system logic to generate a correction signal to move the read/write heads back toward the track centerline until such time as the PES is again zero, indicating that the read/write heads are again properly aligned with the data tracks.
One trend in the disc drive industry is to increase the capacities, or tracks per inch (TPI), of the disc drive while maintaining or reducing the physical sizes, or form factors, of the drive. As the TPI of a disc drive increases, accurately maintaining a head over a desired track becomes increasingly more difficult. As a result, disc drives are becoming increasingly sensitive to vibrations, such as self-excitation of rigid body vibration modes within the disc drive. Generally, the expectation in servo loop design is that both the rotation position actuator and the resultant position of the heads over a given track, as directed by the servo system, and the radial position of servo data within the track, as indicated by the PES, will ideally remain fixed in space. When undesirable linear motion along the plane of the discs and rotational motion of the disc drive base accompany the desired rotational motion of the actuator, the result shows up as xe2x80x9cnoisexe2x80x9d on the PES. As such, the ability of the disc drive servo system to accurately track-follow is compromised in the presence of self-excitation of the disc drive.
Along with the general trend in the industry to provide ever decreasing form factors and ever increasing storage capacities in disc drives, there is also a trend to provide reductions in the level of acoustic emissions generated by disc drives.
Acoustic emissions from disc drives are typically generated from resonant vibrations induced in the disc drive top cover and base by self-excitation of the drive as described above. Additionally, self-excitation of rigid body vibration modes within the disc drive may be transmitted to, for example, the housing of the computer system in which the disc drive is mounted. This transmission typically occurs through brackets which mount the disc drive inside the computer housing. For example, the most common type of disc drive mount is by way of screws connecting the disc drive to a formed compartment or bracket made from sheet steel. As is typical, the screws are raised through holes in the bracket and attached to screw holes at locations around the periphery of the base of the disc drive. Unfortunately, mounting a disc drive in this manner provides a direct, metal-to-metal conduction path for noise and vibrations from the disc drive to be transferred to the housing of the computer.
Attempts have been made to isolate the noise made by disc drive self-excitation from the bracket, and thus the housing of the computer, typically by the use of grommet-like dampers placed along the screws between the disc drive and the bracket. However, results of this type of attachment have often been unsatisfactory. Furthermore, as these dampers can be characterized as springs, the spring-like attributes of the dampers often play a role in the actuator-induced self-excitation response of the disc drive.
A common problem encountered by disc drive manufacturers in designing mounting systems which produce disc drive self-excitation and the resulting noise is that disc drive manufacturers have only minimal-to-moderate control over how customers attach or mount drives. For example, some disc drive users use only a few of the screw positions to mount the disc drive, thus reducing the stability of disc drive mounts. Additional self-excitation problems occur when two or more drives are mounted in adjacent chassis locations. When this occurs, there is no assurance that these drives will be isolated in their dynamic mechanical behavior. This is especially true if one drive is, for example, seeking while the other disc drive is attempting to track follow. The combination of vibrations occurring in the two mounted drives can greatly exacerbate the vibration and noise problem discussed above.
Accordingly there is a need for an approach to mounting a disc drive which helps reduce rigid body vibrations within the disc drive and acoustical emission from the disc drive.
Against this backdrop embodiments of the present invention have been developed. Embodiments of the present invention include a method and apparatus for attaching a data storage device to a stationary planar support surface. In an embodiment of the present invention, an attachment member having first and second sides is attached, via the first side, to an outer planar surface of the data storage device. The attachment member is preferably attached to the outer planar surface such that it extends around or covers a center-of-mass of the disc drive. The second side of the attachment member may then be attached to the stationary planar support surface. In this manner, the disc drive is secured to the stationary planar surface in a manner which reduces or inhibits the rotation of the disc drive about the disc drive center-of-mass, thus reducing the affects of self-excitation in the disc drive.
In a further embodiment of the present invention, the attachment member is preferably annular in shape and formed of a polymeric viscoelastic damping material. In yet another embodiment of the present invention the attachment member preferably comprises an annular shaped polymeric viscoelastic double sided adhesive film positioned symmetrically about the center-of-mass of the disc drive.